chemical physics of discharges - Argonne National Laboratory

O-‘
The initial decrease of the signals from the yellow downstream photomultiplier
is due to NO titration of nitrogen atoms produced in the exciting discharge, &,
The null point represents the complete conversion of nitrogen atoms t;o oxygen atoms.
The concentration of these atoms derived from the amount of NO added to reach this
null is consistent with the intensity of the first positive bands before NO addition.
The linear rise of the yellow sensitive photomultiplier after null is due to
and indicates that 0 is essentially constant.
NO + 0 -+ NO2 + hv (18)
There is a slow increase of the NO y and f3 bands in the excitation bulb because
of the slow increase in the actual steady-state concentration of NO which is main-
tained by
and reaction (16), a,
N + 0 + M -+ NO + M
NO+O+M+N02+M
NO + 0 -+ NO + O2
When [N] goes to zero, this steady state cannot be maintained, and NO in the stream
increases as expected for no reaction of NO. In the reaction time available reaction
(20) does not significantly alter either [O] or [NO].
As [NO] increases sharply after the removal of N, the NO y and f3 bands increase
sharply in the discharge and the N2 Vegard-Kaplan bands decrease rapidly. Since
I Y = [NO(A2E+)]/r,
for excitation in the discharge bulb, and since
(22)